There are a number of available automatic and semi-automatic firearms for use by military personnel and civilians. While fully automatic firearms are generally illegal for use by the civilian population, many of the components which constitute an automatic firearm are the same as those found within legal semi-automatic models. Arguably the most popular semi-automatic assault-type firearm used by civilians, particularly within the United States, is the AR-15. The AR-15 is the semi-automatic variant of the fully automatic M16 firearm used by United States military personnel. While AR-15 is a registered trademark of Colt Industries, a number of additional manufacturers manufacture clones of the AR-15 and market these clones under separate trademarks. While used throughout the specification, it is to be understood that the term AR-15 is meant to include not only those firearms manufactured by Colt Industries, but also those additional clones and any variants thereof.
The AR-15 and M16 are designed as modular rifles generally comprising a buttstock, lower receiver, upper receiver and barrel assembly configured to fire .223 Remington or 5.56×45 mm NATO military ammunition. Each component is separable from one another and affords firearm owners the opportunity to customize the firearm with after-market components such as barrels of differing lengths, upper receivers designed to handle different calibers of rifle ammunition, flashlights, hand guards, grenade or flare launchers, flash or sound suppressors, grips, and front or rear sights. To operate, the lower receiver is configured to include a trigger wherein activation of the trigger causes a rifle cartridge housed within the chamber of the upper receiver to be fired out the barrel of the firearm by action of a reciprocating bolt carrier group. Internal mechanisms of the upper receiver expel the shell casing of the fired rifle cartridge from the chamber while components engaged with the magazine housed within the magazine well of the lower receiver feed a new rifle cartridge into the now-empty chamber. The buttstock mounts to the lower receiver and includes a buffer assembly and action (or recoil) spring in communication with the bolt carrier group where the spring pushes the bolt carrier group back toward the chamber in preparation of firing another rifle cartridge.
To date, most automatic and semi-automatic firearms, like the AR-15, have been configured to fire rifle cartridges only. Attempts to modify these firearms, and particularly the AR-15, to fire shotgun shells have run into a number of problems. For instance, AR-15s have been modified to accommodate .410 bore shells but these modifications require lower receivers which no longer satisfy military specifications (mil-spec). Other modifications continue to result in jamming or binding of the shotgun shell cartridges when a cartridge has been fired, its shell is being ejected, or a new cartridge is being extracted from the magazine and loaded within the chamber. To that end, Applicant has produced a shotgun shell magazine configured to feed shells from the magazine into a mil-spec AR-15/M16 lower receiver (see commonly owned U.S. Pat. No. 9,664,469 (the '469 Patent) issued May 30, 2017, the entirety of which is incorporated by reference herein). Nevertheless, the direct impingement mechanism used within many assault-type rifles (including the M16/AR-15) may hinder or prevent proper ejection of the fired shotgun shell, or may fail to properly cycle the bolt carrier assembly during ejection and extraction.
As such, there is a need for an upper receiver and barrel assembly which is configured to mount to a lower receiver, wherein fired shotgun shells may be efficiently ejected after firing while also properly extracting the next successive shotgun shell from the magazine upon proper cycling of the bolt carrier assembly. There is a further need for a modified M16/AR-15 upper receiver configured to mount to a mil-spec M16/AR-15 lower receiver and automatically or semi-automatically fire .410 bore shotgun shells. The present invention addresses these and other needs.